非线性负载下双馈风力发电系统独立运行改进控制

MODIFIED CONTROL OF STAND-ALONE DOUBLY-FED WIND POWER GENERATION SYSTEM UNDER NONLIEAR LOADS

在深入分析非线性负载下双馈电机(DFIG)数学模型的基础上,针对双馈电机的独立运行提出一种基于积分滑模和改进的扩张状态观测器的直接电压控制方法(DVC)。通过改进的扩张状态观测器(MESO)对积分滑模控制(ISMC)中的直流量和交流量进行估计,设计基于MESO的可ISMC电压控制器,消除谐波,减小非线性负载对电压的影响。该方法仅需采集电压信号,且无需相序分离操作,可简化控制器结构。仿真和实验对比结果表明,所提方法能够准确消除定子电压中的指定频率谐波,提高非线性负载下双馈发电系统的发电电能质量,具有较快的响应速度和优异的稳态性能。

According to the deep analysis to the model of doubly-fed induction generator(DFIG)under nonlinear loads,a direct voltage control method based on integral sliding mode control(ISMC)and a modified extended state observer is proposed for stand-alone DFIG system. The DC component and the AC component of the ISMC are estimated by the MESO accurately. By using the estimated term of the MESO,an MESO-based ISMC voltage regulator is designed. The voltage regulator can eliminate the harmonics in stator voltage and decrease the adverse impact from the nonlinear loads. The implementation of the proposed method only needs the stator voltage signals. The sequence decomposition operations are not required. As a result,the structure of the controller is simplified. The simulation and experiment results indicate that the proposed method can eliminate the harmonics with a specific frequency in stator voltage and improve the power quality of the doubly-fed winder power generation system. Hence,the proposed method has satisfactory dynamic response speed and static performance.